1. Field of the Invention
The present invention relates to a process for producing silicon carbide films and microcomponents via a C.sub.60 precursor.
2. Description of Related Art
Silicon carbide is a promising material for many semiconducting applications, in particular for integrated circuits operating at extremes of temperature, power, speed, or frequency. Silicon carbide has a wide band gap and excellent physical stability, in addition to high electron mobility, thermal conductivity, and hardness. But silicon carbide is not widely used because of the difficulty in growing large-area single crystals and in etching silicon carbide to form the necessary microstructures.
Chemical vapor deposition techniques are currently available to produce silicon carbide thin films from silane or disilane and hydrocarbon gases (e.g., methane) at high substrate temperatures (&gt;1300 K). However, growth is relatively slow and can incorporate hydrogen into the film from the reactants. The hydrogen from the silane and methane are detrimental to device performance. In addition, the high temperatures make the processing expensive. Dry etching techniques for silicon carbide are also available, but are slow and difficult to control to produce clean, smooth surfaces.
The interaction of C.sub.60 clusters with silicon wafers has been studied by the applicants and others (Hamza and Balooch 1,2!; Sakurai et al. 3!; Weaver et al. 4!; and Creager et al. 5!). These studies have shown that at low temperatures, the C.sub.60 cluster adsorbs strongly, but intact, to the clean silicon surface. Balooch and Hamza 2! documented the reaction of C.sub.60 with silicon and observed the opening of the C.sub.60 cage at temperatures &gt;900 K. Hamza and Balooch have also pointed out that the solubility of carbon in silicon is very small at temperatures below 1600 K.
It has been assumed, then, that the carbon desorbs during annealing at &gt;1150 K, and silicon carbide is not formed. Although some researchers (Sakurai et al. 3!; Chen and Sarid 6!) have claimed to observe SiC island nucleation after heating above 1100 K, the scanning tunneling microscopy results do not have sufficient resolution to show the lattice parameter corresponding to SiC. Thus, their claims of SiC islands are unconfirmed.
A process for forming silicon carbide films and microcomponents at low temperatures in a hydrogen-free environment would be advantageous, particularly in making semiconductor devices. The present invention builds on research conducted by the applicants and provides a method for growing silicon carbide on silicon wafers, producing crystalline thin films and patterns via reaction of silicon with C.sub.60.